A Field Survey on Up-stream Migrating Fishes at Takahashi River Estuary Barrage
Proceedings of the International Symposium on Fishways '95
The Organizing Committee for International Symposium on Fishways '95 in Gifu
We surveyed up-stream migration of fishes at Takahashi River Estuary Barrage, where the change of the tide is about 2 meters. As a result, we found the following: (1) In case of the entire overflow type barrage, partial blocking of flow has a large effect on fish attractions. (2) Ripraps below the barrage function as a resting area for up-stream migrating fishes. (3) The number of ascending Ayu and Threadfin goby are related to the tide. (4) Up-stream migration activity of Mitten crab is not related to the tide. They become active when it's dark. (5) Juvenile eels, Mitten crabs, and Long-armed shrimps are able to ascend through the area where there is no fishway. (6) For up-stream migrating fishes, the area below the barrage and the exit of the fishways are dangerous gates where large fisheaters gather.